Golf club head

ABSTRACT

A golf club head is disclosed, which enables a low center of gravity to be achieved without spoiling appearance of the head and reducing strength thereof, and thus enables a carry to be increased. This golf club head has a hollow structure, and includes an opening in a crown portion and a plate member fixed to the opening. The plate member is made of a material having a specific strength of 294 N/mm 2  or higher. For example, this head includes a volume equal to or more than 350 cc, a center-of-gravity retreating amount GR from a shaft axis equal to or more than 15 mm, and a center-of-gravity position ratio GH/FH equal to or lower than 0.61. Here, the ratio GH/FH is calculated from a maximum height FH of a face surface and a center-of-gravity height GH on the face surface.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a golf club head having a hollowstructure. More specifically, the invention relates to a golf club headcapable of increasing a carry by setting a low center of gravity toreduce a spin of a ball and increase a launch angle.

[0002] Conventionally, a metal golf club head having a hollow structurehas been used for a golf club such as a utility club, a fairway wood anda #1 wood. In such a golf club head, because of use of metallicmaterials not only for face and sole portions but also for a crownportion, the center of gravity has been high. Especially, in the case ofusing a titanium material for a deep-face head of the #1 wood, the headhaving a volume of 300 to 400 cc, even if the head is designed based ona limit thickness to secure minimum necessary strength, a limitation onmaximum head weight makes it difficult to adjust a position of a centerof gravity by deviation in a weight distribution. Thus, it has beendifficult to achieve a low center of gravity.

[0003] On the other hand, Japanese patent application Kokai publicationNo. 5-317465 describes a golf club head having no metallic materialsdisposed on the crown portion. However, this golf club head has a holebored on the crown portion, or only has a plate of a lightweight resinor the like attached to the crown portion. Consequently, an appearanceof the head has been bad, and strength thereof has been insufficient.

SUMMARY OF THE INVENTION

[0004] An object of the present invention is to provide a golf club headcapable of achieving a low center of gravity even in the case of aso-called deep-face head without spoiling appearance of the head andwithout reducing strength thereof, thereby reducing a spin of a ball andincreasing a launch angle to increase a carry.

[0005] In order to achieve the foregoing object, a golf club head of thepresent invention includes an opening in a crown portion, and a platemember fixed to the opening, the plate member being made of a materialhaving a specific strength of 294 N/mm² or higher.

[0006] Here, the specific strength is a result of dividing a tensilestrength (N/mm²) by a specific gravity, and it means that as thespecific strength is larger, the strength is higher while weight islight. Accordingly, by replacing a metallic material of the crownportion with the plate member, it is possible to achieve a low center ofgravity even in a so-called deep-face golf club head without spoilingthe appearance of the head and without reducing the strength thereof.The achievement of the low center of gravity enables the spin of a ballto be reduced, the launch angle to be increased, and thus the carry tobe increased to a maximum.

[0007] In order to achieve a satisfactorily low center of gravity of thegolf club head, preferably, a surface area ratio of the plate member toa portion above a position at half a maximum height of the crown portionis set equal to or higher than 20%.

[0008] According to the present invention, it is possible to provide anovel golf club head having a hollow structure, which is provided with aweight distribution that has never existed in the conventional art.

[0009] That is, the present invention provides a golf club head having ahollow structure, which includes a volume equal to or more than 350 cc,a center-of-gravity retreating amount GR from a shaft axis equal to ormore than 15 mm, and a center-of-gravity position ratio GH/FH equal toor lower than 0.61, the ratio GH/FH being calculated from a maximumheight FH of a face surface and a center-of-gravity height GH on theface surface.

[0010] The present invention provides a golf club head having a hollowstructure, which includes a volume equal to or more than 300 cc but lessthan 350 cc, a center-of-gravity retreating amount GR from the shaftaxis equal to or more than 18 mm, and a center-of-gravity position ratioGH/FH equal to or lower than 0.55, the ratio GH/FH being calculated fromthe maximum height FH of the face surface and the center-of-gravityheight GH on the face surface.

[0011] The present invention further provides a golf club head having ahollow structure, which includes a volume equal to or more than 150 ccbut less than 200 cc, a center-of-gravity retreating amount GR from theshaft axis equal to or more than 12 mm, and a center-of-gravity positionratio GH/FH equal to or lower than 0.50, the ratio GH/FH beingcalculated from the maximum height FH of the face surface and thecenter-of-gravity height GH on the face surface.

[0012] The present invention still further provides a golf club headhaving a hollow structure, which includes a volume equal to or more than100 cc but less than 150 cc, a center-of-gravity retreating amount GRfrom the shaft axis equal to or more than 8 mm, and a center-of-gravityposition ratio GH/FH equal to or lower than 0.50, the ratio GH/FH beingcalculated from the maximum height FH of the face surface and thecenter-of-gravity height GH on the face surface.

[0013] Each of the above-described golf club heads can be achieved byproviding an opening in a crown portion, and fixing a plate member madeof a material having a specific strength of 294 N/mm² or higher to theopening. However, it should be understood that a golf club head havingthe above-described weight distribution achieved by other means is alsocontained within the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a front view showing a golf club head according to anembodiment of the present invention.

[0015]FIG. 2 is a side view showing the golf club head of the embodimentof the invention.

[0016]FIG. 3 is a sectional view taken along a line X-X of FIG. 1.

[0017]FIG. 4 is a front view of a peripheral portion of the golf clubhead for illustrating definition of a club length according to theinvention.

[0018]FIG. 5 is a front view of a peripheral portion of a golf club gripfor illustrating the definition of the club length of the invention.

[0019]FIG. 6 is a side view showing an example of measuring device of acenter-of-gravity retreating amount.

[0020]FIG. 7 is a side view showing measurement of the center-of-gravityretreating amount by the measuring device of FIG. 6.

[0021]FIG. 8 is a perspective view showing a measuring device of acenter of gravity of the head.

[0022]FIG. 9 is a side view showing a measuring method of the center ofgravity of the head in a state where the head is mounted on thecenter-of-gravity measuring device.

[0023] FIGS. 10(a) and 10(b) show the measuring method of the center ofgravity of the head: FIG. 10(a) being a side view showing a state wherethe head is mounted on a position balanced with respect to thecenter-of-gravity measuring device; and FIG. 10(b) being a side viewshowing a state where the head is mounted on a position unbalanced withrespect to the center-of-gravity measuring device.

[0024]FIG. 11 is a side view showing a method of checking levelness of asupporting portion of the center-of-gravity measuring device in a statewhere a level is placed on the center-of-gravity measuring device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Next, detailed description will be made for a constitution of thepresent invention with reference to the accompanying drawings.

[0026] Each of FIGS. 1 to 3 shows a golf club head according to anembodiment of the present invention. As shown in FIGS. 1 and 2, the golfclub head of the embodiment has a hollow structure, in which a crownportion 2 and a sole portion 3 are connected to a face portion 1 to becontinuous. This golf club head also includes a hosel portion 4 providedon a heel side for fixing a shaft. As a material constituting the golfclub head, a metallic material such as titanium, aluminum or stainlesssteel can be used.

[0027] In the golf club head, an opening 2 a is provided in the crownportion 2, and a plate member 5 is fixed to the opening 2 a. This platemember 5 is made of a material having a specific strength of 294 N/mm²or higher. The upper limit of the specific strength is not especiallylimited in view of the function, and the higher specific strength can beselected as long as materials having the higher specific strength exist.As a material constituting the plate member 5, a fiber reinforcedplastic is available, which is prepared by impregnating a reinforcedfiber such as a carbon fiber, a glass fiber and an alamido fiber with amatrix resin such as an epoxy resin, an unsaturated polyester resin anda vinylester resin. Especially, the carbon fiber is preferred as areinforced fiber. Preferably, a material constituting the plate member 5has a specific gravity of 0.5 to 2.0.

[0028] By replacing the metallic material of the crown portion 2 withthe plate member 5 made of a material having such a high specificstrength, a weight distribution in an upper part of the head isrelatively reduced to lower a center of gravity G of the golf club head.Moreover, since the plate member 5 is present on the crown portion 2 toprevent exposure of the opening 2 a, the appearance of the head is notspoiled. Since the specific strength of the plate member 5 is high, noreduction occurs in strength of the head. Accordingly, a low center ofgravity can be achieved even in the case of the golf club head having alarge volume and a deep face (face having a vertical width of, e.g., 46mm or more). The lower center of gravity reduces a spin of a ball andincreases a launch angle, thereby enabling a carry to be increased to amaximum.

[0029] In the foregoing golf club head, as shown in FIG. 2, preferably,a surface area ratio of the plate member 5 to a portion above a positionat half a maximum height MH of the crown portion 2 is set equal to orhigher than 20%. Accordingly, by setting the surface area ratio of theplate member 5 equal to or higher than 20%, a satisfactorily low centerof gravity can be achieved for the golf club head. The upper limit ofthe surface area ratio is not especially limited in view of thefunction. The upper limit, however, is preferably set to 90% inconsideration of the structure of the golf club head.

[0030] The plate member 5 can be adhered to the opening 2 a of the crownportion 2. For example, as shown in FIG. 3, a step is formed on aperipheral edge of the opening 2 a of the crown portion 2. On the otherhand, a peripheral edge of the plate member 5 is processed to match thestep and adhered to the opening 2 a. When necessary, a plate member 6made of a similar material to the plate member 5 may be adhered to theplate member 5 from the inner side of the head. Accordingly, the platemember 5 can be firmly fixed to the crown portion 2. Needless to say,the method of fixing the plate member 5 is not limited to the above, butother methods can be used. The presence of the plate member 5 isapparent in the drawing, but the appearance of the golf club head is notaffected at all if paint is applied.

[0031] According to the present invention, the following golf club headscan be constructed.

[0032] As a first golf club head, a golf club head is provided, whichincludes a volume equal to or more than 350 cc, a center-of-gravityretreating amount GR from a shaft axis S equal to or more than 15 mm,and a center-of-gravity position ratio GH/FH equal to or lower than0.61, more preferably equal to or lower than 0.55, the ratio GH/FH beingcalculated from a maximum height FH of a face surface 1 a and acenter-of-gravity height GH on the face surface 1 a. In this case, theupper limit of the volume of the golf club head is not especiallylimited in view of the function. The upper limit, however, is preferablyset to 600 cc, preferably 500 cc, more preferably 400 cc in order toobtain necessary strength to the hit ball.

[0033] As a second golf club head, a golf club head is provided, whichincludes a volume equal to or more than 300 cc but less than 350 cc, acenter-of-gravity retreating amount GR from the shaft axis S equal to ormore than 18 mm, and a center-of-gravity position ratio GH/FH equal toor lower than 0.55, more preferably equal to or lower than 0.50, theratio GH/FH being calculated from the maximum height FH of the facesurface 1 a and the center-of-gravity height GH on the face surface 1 a.

[0034] As a third golf club head, a golf club head is provided, whichincludes a volume equal to or more than 150 cc but less than 200 cc, acenter-of-gravity retreating amount GR from the shaft axis S equal to ormore than 12 mm, and a center-of-gravity position ratio GH/FH equal toor lower than 0.50, the ratio GH/FH being calculated from the maximumheight FH of the face surface 1 a and the center-of-gravity height GH onthe face surface 1 a.

[0035] As a fourth golf club head, a golf club head is provided, whichincludes a volume equal to or more than 100 cc but less than 150 cc, acenter-of-gravity retreating amount GR from the shaft axis S equal to ormore than 8 mm, and a center-of-gravity position ratio GH/FH equal to orlower than 0.50, the ratio GH/FH being calculated from the maximumheight FH of the face surface 1 a and the center-of-gravity height GH onthe face surface 1 a.

[0036] Here, the center-of-gravity retreating amount GR means a distancebetween a center of gravity G of the head and a plane containing theshaft axis S and vertical to a reference surface B in a state where thehead is placed on the reference surface B according to a lie angle, andthe face surface 1 a is directed to a target line.

[0037] The placement according to the lie angle means that gaps betweena round of the sole surface of the head and a placement surface made ofa plane are roughly equal to each other at toe and heel sides. If theround of the sole surface is unclear, the placement of the head is madesuch that a score line and the placement surface are parallel to eachother. If the round of the sole surface is unclear, and the placementsurface and the score line cannot be determined to be parallel to eachother, for example in the case where the score line is not linear, thehead is placed with the lie angle (degree) (=100−club length (inch)).For example, if the club length is 44 inches, the lie angle is 56°(=100−44).

[0038] The club length is measured by a measuring method set up by theJapan Golf Goods Association. As a measuring device, Club Measure II byKamoshita Seikojo Co., Ltd., or the like is available. That is, as shownin FIGS. 4 and 5, when a heel end is set as a base point P₁, and a gripend is set as an end point P₂, then a distance C between the points P₁and P₂ is set as the club length.

[0039] As shown in FIG. 6, the above-described center-of-gravityretreating amount GR is measured by a seesaw balance 10 swingable in anarrow direction U around a fulcrum 11. The balance 10 includes a shaftpin 12 to be fitted into the hosel hole of the head without any gapstherebetween. The balance 10 is balanced in such a way as to set an arm13 horizontal while no heads or heavy bodies are placed thereon. Here,as shown in FIG. 7, a head 31 of mass W is fitted over the shaft pin 12extended in a vertical direction. The head 31 is then rotated and fixedso as to enable the center-of-gravity retreating amount GR to bemeasured in an arm longitudinal direction. In other words, thecenter-of-gravity retreating amount GR coincides with a distance Lbetween a plane P passed through the fulcrum and set orthogonal to thearm longitudinal direction and the center of gravity G of the head 31.In the side view of the balance 10, the face surface 1 a is somewhatseen because of presence of a loft angle and the lie angle in the head31.

[0040] Then, by using a heavy body 14 of mass W′, a length L′ from acenter of gravity G′ of the heavy body 14 to the fulcrum is selectedsuch that the arm 13 is horizontally balanced. As a result, thecenter-of-gravity retreating amount GR can be calculated byGR=L=(W′×L′)/W based on an equation of equilibrium W×L=W′×L′. The abovedescription has been made on the principle of measuring thecenter-of-gravity retreating amount GR from the shaft axis. As ameasuring device, a center-of-gravity measuring device by KamoshitaSeikojo Co., Ltd., can be used.

[0041] On the other hand, as shown in FIG. 3, the maximum height FH ofthe face surface is a height from the reference surface B to a highestposition of the face surface 1 a while the head is placed on thereference surface B according to the lie angle, and the face surface 1 ais directed to the target line. The center-of-gravity height GH on theface surface is a height from the reference surface B to a point g in aplacement state of the head similar to the above when a center ofgravity position on the face surface 1 a is obtained, the center ofgravity position being composed of the point g at which a perpendicularfrom the center of gravity G to the face surface 1 a intersects the facesurface 1 a.

[0042] The point g on the face surface 1 a of the head is obtained by acenter-of-gravity measuring device 41 similar to that shown in FIG. 8.The center-of-gravity measuring device 41 includes a supporting portion42 for supporting an article to be measured for a center of gravitythereon. This supporting portion 42 supports the article to be measuredin a balanced manner, and a position of the article can be known. Thatis, when the center-of-gravity position on the face surface 1 a isobtained, as shown in FIG. 9, the head 31 is mounted on the supportingportion 42, and an equilibrium position, at which the head 31 does notfall off even with hands off the head, is searched. In other words, asshown in FIG. 10(a), if the point g is contained in a contact portionbetween the face surface 1 a and the supporting portion 42, the head 31mounted on the supporting portion 42 will not fall off even with handsoff the head. However, as shown in FIG. 10(b), if the point g is notcontained in the contact portion between the face surface 1 a and thesupporting portion 42, the head 31 mounted on the supporting portion 42will fall off with hands off the head. The point g is obtained based onthis.

[0043] Preferably, the supporting portion 42 supports the article on aplane or at three points or more. Preferably, an area of the supportingportion 42 is set equal to 15 mm² or less. There is no lower limit onthe area as long as the head 31 can be supported. The area of thesupporting portion 42 is represented by an area of a planar part in thecase of the support on the plane, and by an area of a figure connectingthe respective points in the case of the support at three points ormore. By setting the area of the supporting portion in the above range,the point g can be obtained more accurately.

[0044] Preferably, the plane formed by the supporting portion 42 becomeshorizontal or substantially horizontal. Here, the state of beingsubstantially horizontal means that an inclination with respect to ahorizontal plane is within 2°, preferably within 1°. The state of beingeither horizontal or substantially horizontal can be checked by mountingand supporting a plate 51 on the supporting portion 42, and placing alevel 52 on the plate 51. By setting the inclination of the plane of thesupporting portion 42 within the above range, the point g can beobtained more accurately.

[0045] The foregoing center-of-gravity retreating amount GR is animportant factor for lofting a hit ball. The upper limit of thecenter-of-gravity retreating amount GR is not especially limited in viewof the function. The upper limit, however, is preferably set to, inconsideration of arrangement of the hosel position and weightdistribution of the golf club head, 70 mm when the volume is equal to ormore than 350 cc, 70 mm when the volume is equal to or more than 300 ccbut less than 350 cc, 55 mm when the volume is equal to or more than 150cc but less than 200 cc, or 50 mm when the volume is equal to or morethan 100 cc but less than 150 cc. By setting the center-of-gravityretreating amount GR in the above range, a sufficient launch angle canbe obtained.

[0046] The center-of-gravity position ratio GH/FH is an index forsetting a low center of gravity. The lower limit of thecenter-of-gravity position ratio is not especially limited in view ofthe function. The lower limit, however, is preferably set to, inconsideration of weight distribution of the golf club head, 0.35 whenthe volume is equal to or more than 350 cc, 0.33 when the volume isequal to or more than 300 cc but less than 350 cc, 0.30 when the volumeis equal to or more than 150 cc but less than 200 cc, 0.30 when thevolume is equal to or more than 100 cc but less than 150 cc. By settingthe center-of-gravity position ratio in the above range, a sufficientcarry can be obtained.

[0047] Especially, if the volume of the head is set large as in thecases of the first and second golf club heads, it is possible toincrease the center-of-gravity retreating amount GR as much as possible,and reduce the center-of-gravity position ratio GH/FH as much aspossible without adding any heavy bodies.

[0048] On the other hand, if the volume of the head is set small as inthe cases of the third and fourth golf club heads, it is possible toincrease the center-of-gravity retreating amount GR as much as possible,and reduce the center-of-gravity position ratio GH/FH as much aspossible without using any metals of high specific gravity such asexpensive tungsten as the heavy bodies.

EXAMPLES

[0049] With regard to a titanium alloy golf club head having a hollowstructure, golf club heads of examples 1 to 4 and comparative examples 1to 4 were respectively manufactured, in which the volumes, thecenter-of-gravity retreating amounts GR and the center-of-gravityposition ratio GH/FH were varied as shown in Table 1. In each of thegolf club heads of the examples 1 to 4, an opening was provided in thecrown portion, and a plate member made of carbon reinforced plastichaving a specific strength of about 1415 N/mm² was fixed to the opening.The surface area ratio of the plate member to the portion above theposition at half the maximum height of the crown portion is as shown inTable 1.

[0050] Golf clubs having the forgoing golf club heads fixed wererespectively prepared. Test hitting was carried out by a swing robot ata head speed of 40 m/s while a sweet spot of each golf club head was setas a hitting position, and the spin, the launch angle and the carry wereevaluated. Results thereof are shown in Table 1. The results of theevaluation are represented by indexes using those of the comparativeexamples 1 to 4 corresponding to the examples 1 to 4 set as 100. Thespin is better as the index value thereof is smaller, and the launchangle and the carry are better as the index values thereof are larger.TABLE 1 Surface area ratio of plate Volume GR member Launch (cc) (mm)GH/FH (%) Spin angle Carry Comparative 396 14.2 0.62 — 100 100 100example 1 Example 1 400 16.2 0.51 30.8  94 106 112 Comparative 310 16.00.56 — 100 100 100 example 2 Example 2 335 19.1 0.47 32.0  92 108 113Comparative 170 13.0 0.53 — 100 100 100 example 3 Example 3 151 15.00.48 27.5  96 105 109 Comparative 135 10.0 0.55 — 100 100 100 example 4Example 4 128 12.0 0.46 24.5  97 104 106

[0051] As understood from Table 1, compared with the correspondingcomparative examples 1 to 4, the examples 1 to 4 have less spins, largerlaunch angles and longer carries.

[0052] According to the present invention, in the golf club head havinga hollow structure, by providing the opening in the crown portion andfixing the plate member made of a material having a specific strength of294 N/mm² or higher to the opening, a low center of gravity can beachieved even in the case of the deep face head without spoiling theappearance of the head and without reducing the strength thereof. Thus,it is possible to reduce the spin and increase the launch angle, therebyincreasing the carry.

[0053] Also, according to the present invention, by providing each offollowing golf club heads (1) to (4), which is provided with a weightdistribution that has never existed in the conventional art, a lowcenter of gravity can be achieved. Thus, it is possible to reduce thespin and increase the launch angle, thereby increasing the carry.

[0054] (1) A golf club head having a hollow structure, which includes avolume equal to or more than 350 cc, a center-of-gravity retreatingamount GR from a shaft axis equal to or more than 15 mm, and acenter-of-gravity position ratio GH/FH equal to or lower than 0.61, theratio GH/FH being calculated from a maximum height FH of a face surfaceand a center-of-gravity height GH on the face surface.

[0055] (2) A golf club head having a hollow structure, which includes avolume equal to or more than 300 cc but less than 350 cc, acenter-of-gravity retreating amount GR from the shaft axis equal to ormore than 18 mm, and a center-of-gravity position ratio GH/FH equal toor lower than 0.55, the ratio GH/FH being calculated from the maximumheight FH of the face surface and the center-of-gravity height GH on theface surface.

[0056] (3) A golf club head having a hollow structure, which includes avolume equal to or more than 150 cc but less than 200 cc, acenter-of-gravity retreating amount GR from the shaft axis equal to ormore than 12 mm, and a center-of-gravity position ratio GH/FH equal toor lower than 0.50, the ratio GH/FH being calculated from the maximumheight FH of the face surface and the center-of-gravity height GH on theface surface.

[0057] (4) A golf club head having a hollow structure, which includes avolume equal to or more than 100 cc but less than 150 cc, acenter-of-gravity retreating amount GR from the shaft axis equal to ormore than 8 mm, and a center-of-gravity position ratio GH/FH equal to orlower than 0.50, the ratio GH/FH being calculated from the maximumheight FH of the face surface and the center-of-gravity height GH on theface surface.

[0058] The preferred embodiments of the present invention have beendescribed in detail. However, it should be understood that variouschanges, modifications and substitutions can be made without departingfrom the spirit and the scope of the invention as specified in appendedclaims.

What is claimed is:
 1. A golf club head having a hollow structure,comprising: a crown portion; an opening in the crown portion; and aplate member fixed to the opening, the plate member being made of amaterial having a specific strength of 294 N/mm² or higher.
 2. A golfclub head having a hollow structure, the head including: a volume equalto or more than 350 cc; a center-of-gravity retreating amount GR from ashaft axis equal to or more than 15 mm; and a center-of-gravity positionratio GH/FH equal to or lower than 0.61, the ratio GH/FH beingcalculated from a maximum height FH of a face surface and acenter-of-gravity height GH on the face surface.
 3. A golf club headhaving a hollow structure, the head including: a volume equal to or morethan 300 cc but less than 350 cc; a center-of-gravity retreating amountGR from a shaft axis equal to or more than 18 mm; and acenter-of-gravity position ratio GH/FH equal to or lower than 0.55, theratio GH/FH being calculated from a maximum height FH of a face surfaceand a center-of-gravity height GH on the face surface.
 4. A golf clubhead having a hollow structure, the head including: a volume equal to ormore than 150 cc but less than 200 cc; a center-of-gravity retreatingamount GR from a shaft axis equal to or more than 12 mm; and acenter-of-gravity position ratio GH/FH equal to or lower than 0.50, theratio GH/FH being calculated from a maximum height FH of a face surfaceand a center-of-gravity height GH on the face surface.
 5. A golf clubhead having a hollow structure, the head including: a volume equal to ormore than 100 cc but less than 150 cc; a center-of-gravity retreatingamount GR from a shaft axis equal to or more than 8 mm; and acenter-of-gravity position ratio GH/FH equal to or lower than 0.50, theratio GH/FH being calculated from a maximum height FH of a face surfaceand a center-of-gravity height GH on the face surface.
 6. The golf clubhead according to any one of claims 2 to 5, wherein an opening isprovided in a crown portion, and a plate member made of a materialhaving a specific strength of 294 N/mm² or higher is fixed to theopening.
 7. The golf club head according to claim 1, wherein a surfacearea ratio of the plate member to a portion above a position at half amaximum height of the crown portion is set equal to or higher than 20%.8. The golf club head according to claim 6, wherein a surface area ratioof the plate member to a portion above a position at half a maximumheight of the crown portion is set equal to or higher than 20%.